This study examines the extent to which heterogeneous environmental attitudes influence recreational demand in a river basin and the valuation of recreational benefits. We first employed a latent class analysis to reveal two distinct classes of respondents that differ in their environmental attitudes despite representing similar demographic characteristics. We then estimated a recreational demand model conditional on respondent's latent class membership after controlling for the probabilistic nature of the membership classification. We found that environmental attitudes directly influence consumer recreational demand and valuation. Ignoring preference heterogeneity leads to overestimation of the recreational benefits.